Re: [PATCH v1 6/7] virtio-mem: use page_offline_(start|end) when setting PageOffline()
From: Mike Rapoport <rppt@kernel.org>
Date: 2021-05-02 06:34:03
Also in:
linux-fsdevel, linux-hyperv, lkml
On Thu, Apr 29, 2021 at 02:25:18PM +0200, David Hildenbrand wrote:
quoted hunk ↗ jump to hunk
Let's properly use page_offline_(start|end) to synchronize setting PageOffline(), so we won't have valid page access to unplugged memory regions from /proc/kcore. Signed-off-by: David Hildenbrand <redacted> --- drivers/virtio/virtio_mem.c | 2 ++ mm/util.c | 2 ++ 2 files changed, 4 insertions(+)diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c index 10ec60d81e84..dc2a2e2b2ff8 100644 --- a/drivers/virtio/virtio_mem.c +++ b/drivers/virtio/virtio_mem.c@@ -1065,6 +1065,7 @@ static int virtio_mem_memory_notifier_cb(struct notifier_block *nb, static void virtio_mem_set_fake_offline(unsigned long pfn, unsigned long nr_pages, bool onlined) { + page_offline_begin(); for (; nr_pages--; pfn++) { struct page *page = pfn_to_page(pfn);@@ -1075,6 +1076,7 @@ static void virtio_mem_set_fake_offline(unsigned long pfn, ClearPageReserved(page); } } + page_offline_end();
I'm not really familiar with ballooning and memory hotplug, but is it the
only place that needs page_offline_{begin,end} ?
quoted hunk ↗ jump to hunk
} /*diff --git a/mm/util.c b/mm/util.c index 95395d4e4209..d0e357bd65e6 100644 --- a/mm/util.c +++ b/mm/util.c@@ -1046,8 +1046,10 @@ void page_offline_begin(void) { down_write(&page_offline_rwsem); } +EXPORT_SYMBOL(page_offline_begin);
Should have been a part of the previous patch.
void page_offline_end(void)
{
up_write(&page_offline_rwsem);
}
+EXPORT_SYMBOL(page_offline_end);Ditto
-- 2.30.2
-- Sincerely yours, Mike.